add CachingPool remotecall_fetch test

Author: IanButterworth

test/distributed_exec.jl

@@ -713,6 +713,7 @@ pmap(_->myid(), 1:nworkers())  # priming run
 @test nworkers() == length(unique(remotecall_fetch(()->pmap(_->myid(), 1:100), id_other)))
 
 # Same tests with custom worker pools.
+# WorkerPool
 wp = WorkerPool(workers())
 @test nworkers() == length(unique(pmap(_->myid(), wp, 1:100)))
 @test nworkers() == length(unique(remotecall_fetch(wp->pmap(_->myid(), wp, 1:100), id_other, wp)))
@@ -723,6 +724,17 @@ wp = WorkerPool(2:3)
 wp = WorkerPool(2:2)
 w = take!(wp)
 
+# CachingPool
+wp = CachingPool(workers())
+@test nworkers() == length(unique(pmap(_->myid(), wp, 1:100)))
+@test nworkers() == length(unique(remotecall_fetch(wp->pmap(_->myid(), wp, 1:100), id_other, wp)))
+wp = CachingPool(2:3)
+@test sort(unique(pmap(_->myid(), wp, 1:100))) == [2,3]
+
+# wait on caching pool
+wp = CachingPool(2:2)
+w = take!(wp)
+
 # local call to _wait
 @test !isready(wp)
 t = @async wait(wp)